My gf shared her fetish of BBC. Idk how should I react

I’m M 20 and my girl is 19 we both are virgin in, but we had oral few times, once night we were taking around fetish and all, at that time she mentioned of getting fucked my bbc once having threesome and all. I wasn't sure how I should react to her that time so l kind of appreciate that time. But I don't really want her to be fucked by any other guy in India or outside India.

She is into travel and she might visit America and Africa someday, and I don't know if I stop she might cheat me for that. How should I confront.